This section provides background information related to the present disclosure which is not necessarily prior art.
Weight reduction for fuel economy in vehicles has spurred the use of various lightweight metal components, such as aluminum and magnesium. While use of such lightweight metals serves to reduce overall weight and generally improves fuel efficiency, these metals also have relatively high linear coefficients of thermal expansion, as compared to traditional steel or ceramic materials. In component assemblies, the use of such lightweight metals can cause uneven thermal expansion under certain thermal operating conditions relative to adjacent components having lower linear coefficients of thermal expansion, like steel or ceramic materials.
For certain applications, especially in power train units and bearing assemblies, appropriate preloading and clearance within the bearing assembly maintains efficiency of performance, while uneven thermal expansion can cause spin loss and thus diminish performance and fuel efficiency. In the past, various components in bearing assemblies, including the housing and bearings themselves, were formed of similar materials like steel or ceramic, which share similar linear coefficients of thermal expansion. Thus, fluctuations in temperature during operation of the vehicle for conventional systems with materials having similar linear coefficients of thermal expansion did not result in significant volumetric changes affecting preloading or clearance in bearing assemblies or other component assemblies.
While the use of the lightweight metal components has the potential to reduce fuel economy gains attributable to weight reduction, the variability and inconsistency of bearing clearances due to the substantial differences in linear coefficients of thermal expansion can potentially result in significant spin loss and other decreased performance efficiency. In particular, automotive systems have various planar components comprising lightweight metals (having relatively high linear coefficients of thermal expansion) adjacent to other components comprising traditional materials (having lower linear coefficient of thermal expansion) thereby result in uneven linear thermal expansion of the various planar components throughout the automotive system. Thus, systems and methods for diminishing thermal expansion in at least one linear direction in automotive systems having various planar components comprising both lightweight metals and other components comprising traditional materials would be desirable to control such linear thermal expansion and further improve efficiency of operation and fuel economy.